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You go to start your car only to discover that the engine won't start and the headlights won't turn on. That's a sign that it's time to check the battery. Not sure how? Don't worry—this article will walk you through how to check your car battery step by step with either a voltmeter or a power probe. If you don't have either of those things, we'll also show you how to check the battery by cranking the engine.
Steps
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Turn your ignition off. [1] X Research source
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Remove the battery's positive terminal cover. Check and clean the battery terminals.Advertisement -
Connect your voltmeter's positive lead to the positive terminal on your battery. The positive lead on a voltmeter is usually red. [2] X Research source
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Attach the negative voltmeter lead to the negative battery terminal.
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Check the voltmeter. If your battery is in good condition, the voltage should be between 12.4 and 12.7 volts. A reading lower than 12.4 volts means that your battery needs to be charged. [3] X Research source
- If the reading is lower than 12.2 volts, "trickle charge" the battery, which is a slow charge. And then re-check.
- If the reading is over 12.9 volts, you have excessive voltage. Turn on the high beams to remove excessive voltage surface charge. Over voltage may be an indication the alternator is over charging the battery.
- While you have the voltmeter handy, you may also want to do load testing .
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Remove the battery's positive terminal cover.
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Connect your Power Probe's positive lead to the positive terminal on your battery. The positive lead on a voltmeter is usually red.
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Attach the Power Probe's negative lead to the negative battery terminal.
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Connect the tip of the probe to the positive battery terminal . Check the probe for voltage reading.
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Check the Power Probe reading. If your battery is in good condition, the voltage should be between 12.4 and 12.7 volts. [4] X Research source
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"Crank" the engine by turning the ignition until the starter engages and hold for 2 seconds Have an assistant crank the engine while you check battery voltage drop.
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At the time of the crank, check the reading of the Power Probe. It should not go below 9.6 volts. [5] X Research source
- A battery with a volt reading less than 9.6 volts means the battery is sulfated and not holding/accepting the charge.
- Alternatively, you can get the battery tested at an auto parts store or a repair shop. [6]
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Expert Source
Jason Shackelford
Auto Technician Expert Interview. 11 June 2019. - They usually test your battery at no charge. [7]
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Expert Source
Jason Shackelford
Auto Technician Expert Interview. 11 June 2019. - Home diagnosis is rather difficult and not very accurate. [8]
X
Expert Source
Jason Shackelford
Auto Technician Expert Interview. 11 June 2019.
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Tips
- Most car batteries last between 4 and 5 years. In hot climates, they may only last about 3 years. If you charge your battery and find that it won't hold a charge while your car isn't running, replace the battery. [9] X Research sourceThanks
- You can test and charge your battery at your local auto parts store.Thanks
- Before buying a new alternator, have the system checked more thoroughly.Thanks
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Warnings
- Never short between battery terminals. Serious burns, damage to the terminals or an explosion from hydrogen gas can occur.Thanks
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Things You'll Need
- Voltmeter
References
- ↑ https://carfromjapan.com/article/car-maintenance/how-to-test-a-car-battery/
- ↑ https://youtu.be/COJr7OB23Hw?t=87
- ↑ https://www.jdpower.com/cars/shopping-guides/how-to-test-a-car-battery-with-a-multimeter
- ↑ https://www.jdpower.com/cars/shopping-guides/how-to-test-a-car-battery-with-a-multimeter
- ↑ https://youtu.be/COJr7OB23Hw?t=35
- ↑ Jason Shackelford. Auto Technician. Expert Interview. 11 June 2019.
- ↑ Jason Shackelford. Auto Technician. Expert Interview. 11 June 2019.
- ↑ Jason Shackelford. Auto Technician. Expert Interview. 11 June 2019.
- ↑ https://www.forbes.com/wheels/advice/how-long-do-car-batteries-last/
About This Article
Article Summary
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To check a car battery, turn off the ignition and pop your vehicle's hood. Hook up a voltmeter to the car's battery by connecting the red lead to the positive terminal and the black lead to the negative terminal. If the battery is in good condition, the voltage will read between 12.4 and 12.7 volts. A reading lower than 12.4 volts means your battery needs to be charged. If the reading is over 12.9 volts, you may want to consider having the alternator checked by a professional to figure out why this is happening! To learn more from our Master Mechanic co-author, like how to use a power probe, keep reading the article!
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